Will L wrote:The wheels are from Alan Gibson, and I was a little surprised to discover that they no longer come with the crankpin hole moulded in.

I'm a bit surprised at that - did you get the wheels recently? I got some wheels from AG three weeks ago and certainly they came with a moulded hole for the crankpin. Also, I quote from AG's catalogue: "Our own wheels have a hole of the correct size moulded but if this does need to be opened out a No.70 (070mm.) drill should be used"

DaveyTee wrote:I'm a bit surprised at that - did you get the wheels recently?DT

I do hope this is not an on-going trend because that is going to make modelling in S4 very difficult for those of us without access to some machine tools. It was bad enough the loss of Sharman wheels to the general modeller as opposed to the kit manufacturer.

I have had AG wheels with and without holes over the years from AG himself, my understanding is that the 'dimple' versions are those from the original Studiolith tooling. There is a comment on the current AG website indicating that they plan to remove the need for customer drilling when they get a round tuit.RegardsKeith

DaveyTee wrote:I'm a bit surprised at that - did you get the wheels recently?DT

I do hope this is not an on-going trend because that is going to make modelling in S4 very difficult for those of us without access to some machine tools. It was bad enough the loss of Sharman wheels to the general modeller as opposed to the kit manufacturer.

I think it depends on what wheels you purchase and the age of the moulds used for the plastic centres. AFAIK, some Gibson wheels have always had the dimples to mark where the hole is supposed to be drilled whilst others have the crankpin holes moulded in. Some kind of jig to drill the holes (such as the one used by Will) is pretty much essential - I know, I've tried to do it without one!

[Edit] Oops, beaten to it by Keith, that'll teach me to go off for a cuppa mid-post..

" Below is a reply I sent to a customer the other day, please forgive the regurgitation as we are busy.

The oldest tooling (which equates with the most popular patterns) was produced with a pip where the crank pin should be. In the bad old days the modeller was expected to drill out his own crankpin hole to suit which ever system he was using. Without looking I can tell you that the standard GWR and Midland 4’7” wheels are like that along with the Terrier to mention 3. This is effectively what is holding up the self quartering wheels as the ones we want to produce first have the pip rather than a hole. It seem ridiculous to produce a self quartering wheel where the user needs to drill out the crank pin hole, so we will be modifying the tool. This has turned it from a new pin for the tool to a potential tool wrecking exercise.

If your look at our crankpin instructions (which haven’t changed from when Alan had the business) there is scope within them covering the older tooling.

There are far more wheels with a hole in than without.

Clearly producing wheels without a crankpin hole is a backward step. I’d be grateful if you could put the record straight on Scalefour forum, and possibly provide me with the contact details for the person responsible.

Assembling the wheels on the axle, and quartering them, is a job I try very hard to do only once per axle. Repeatedly removing and remounting the wheels is a recipe for having them move on the axle, and lose quartering, in service. Using CSBs (or any other horn block base system for that matter) should mean once only assembly is eminently achievable. Of course this does mean you have to get the thickness of the washers behind the driving wheels right before the first assembly.

There are two ways of doing this. The first is by very careful measurement, which I’m sure some of you could manage. The second is to have a sacrificial pair of wheels which you can assemble on the axle with the axle block and washers, repeatedly if necessary, so you can check it all goes in the frames with the required amount of free play. The sacrificial wheels have to be the same basic width as the real ones but need not be the same diameter. With Gibson wheels just make sure the raised hub at the back stands proud of the wheel rims by the same amount. Once you have one pair you can use them to make many chassis.

On the J10 the intention was that the font and back axles would be washered up until there is no appreciable free play, and the centre axle would have no washers at all, giving in the region of 1.5mm lateral movement, which is more than it needs. The moulded hub on the back of the wheel is enough to keep the rims away from the frames so I didn’t see any need to add any more washers..

I tried the measurement system and I got it wrong. I started on the front axle and it was just too tight over the frames. So after that I had a sacrificial pair of wheels and all the washer combinations had been tried and refined to perfection before the real service wheels were fitted. And yes I did buy a new pair of wheels, which needed drilling etc, but at least I was getting good at that by then.

Quartering made easy

I assemble the wheels in a GW wheel press, which presses on and quarters the wheels all in one go. This is a tool I would happily recommend to anybody. It is made to do the business in a vice but I find, on Gibson wheels at least, I can squeeze it together by hand just as well. They come out square on the axle and correctly quartered. I haven’t had a chassis problem caused by poor quartering since I brought it.

The following photo shows the GW press tool with everything in place to fit the wheels on the gearbox axle. For those not familiar with the this tool, the wheels aren't just sitting in some arbitrary place between two big lumps of aluminium. What you can't see in the picture are the sprung stub axles the wheels are mounted on, and the slots the crank pins fit into to keep the correct quartering angle. The dark lump in the middle behind the axle is the back to back gauge which you need to have in there. The GW press would work without a back to back gauge but you would then be reliant on the stops on the sub axles in the jig being adjusted exactly right for the length of the axle being used. I don’t think the odds on that are good, so I do it round a back to back gauge.

csb W&M 4.jpg (248.09 KiB) Viewed 9996 times

I use Loctite 603 to lock the wheels on the axles, I smear a small quantity round both ends of the axle just prior to pressing the wheels on. There is a danger that the 603 will flow up the axle and into the axle blocks, locking them to the axle too. Yes this is experience talking, but not on the J10. To stop this happening I put a couple of turns of cotton thread around the axle either side of the selection of washers, axle bearings and gearbox bits which need to be mounted on the axle. In the picture this thread is black, which was a poor choice photographically. The thread not only absorbs any errant 603 but also keeps all the loose bits together in the middle and as far out of the way as possible.

You may remember, way back in an earlier post, I talked about identifying which side of the chassis a parts belongs on by centre pop marks. One pop for things on the left side seen from above facing forward, and two on the other side. You will note that the GW press is also so marked just to ensure I use it the same way round on each wheel set.

In all the excitement I seem to have forgotten to remind you that, as the axle blocks are matched to a specific horn guide, you must be most careful to get the right axle block on the right end of the right axle. This is after all what the centre pop marks are all about, and why the press tool carries the same marks.

Nicely described Will! I echo your sentiments about the GW wheel press - wouldn't be without it.

There's another little trick you can use to avoid the Loctite spreading up the axle to the bearings - yes, it's happened to me too!

Firstly, degrease the axle ends and wheel hubs with IPA (Isopropyl alcohol), then install the axles as Will describes, but only advancing them about a mm or so into the wheels, before retracting the blocks of the press just enough to release the wheels so you can introduce a little Loctite using a cocktail stick onto the outside of the axle, now within the wheel. Then re-apply the jig and continue as described. As soon as the wheels are mounted to correct B to B, I pull the jig apart, removing the stub axles from the jig and cleaning them before the Loctite hardens and sets them solid within the jig! Not really a problem - the fit is quite loose and they can be drifted out easily after removing the grub screw. It sounds fiddly, but it does ensure a good bond without seizing everything up. It's still a lot quicker than doing the quartering in the time honoured method and it's less likely to move.

Having mounted and quartered three sets of wheels, the time has come to fit them into the chassis. The axle blocks are slid back into the horn guides they were matched with. Then the CSB wires are inserted through all the fulcrum points. The wires need to be well over length and have one end turned over into an L shape. This will stop it sliding right through by accident, and gives you something to hold onto while trying to manoeuvre the ... thing through all the fulcrum points.

Both getting the axle blocks into the horn guides and inserting the CSB wires through the fulcrum points can be a bit fiddly. Thin nosed pliers and a bit of patience are the tools you’ll need to guide them in. I prefer to use axle washers that are wider than the cut out in the frame for the horn guide. Smaller ones can become caught in the cut out and prevent the axle block fitting back into the horn guide. Then, the better your design lines up the fulcrum points, the easier getting the wires in will be.

If you put all the wheels in at once, you will probably find the wheels at one end will drop out again, while you’re struggling to get the first wire in at the other. It's better to put in just one pair of end wheels, push one wire in as far as the fulcrum point beyond that wheel set, then move on to the next pair etc.

It is at this point that one of the great joys of this form of CSBs becomes apparent. The wheels are retained in the chassis by the wires. There is no need for a keeper plate or the soft wire ties through the eyes in the horn guides that we used to keep the axle block/horn guide pairs together in the early stages. Then if you want the wheels out again, you pull out the wires and the wheels drop out just like that.

CSB W&M 11.jpg (169.2 KiB) Viewed 9917 times

The picture shows the wires in place. Note the turned over ends and the centre pop marks on the axle blocks (see previous post).

One more thing, just because you’ve fitted sprung suspension, it doesn’t mean you don’t need to start with a basic square and flat chassis. To check it is as flat as it should be, the first set of CSB wires I fitted are 20thou steel wire. These don't have a lot of give, and, as there is no body weight either, bend very little unless pushed. A chassis that isn't flat will show a lifted wheel or two if placed on that piece of plate glass we all had for checking rigid chassis. Do remember that it won’t sit flat if either of the wires has missed a fulcrum point. These thick wires stay in the chassis until I'm ready to try the ride height with the finished body, only then do I fit the correct size wire.

Next up comes the coupling rods, and the first thing that needs attention are the crank pin holes. Up to now these have been sized to fit the pins on the chassis jig they were constructed on. They now needed to fit the AG crank pin bushes, which, by a feat of good management, are a bit larger.

I like to use a fine taper reamer for this job. I work on one hole until I have a comfortable fit on the bush, with just a smidgen of clearance. Then I mark my place on the reamer by wrapping a bit of masking tape around it at the point I have been reaming up to. Using that as a guide, I then reamed all the holes the same size. Remember to finish the reaming from both sides to eliminate as much as possible of the slight taper in the hole. It can be quite hard on the fingers to remove a lot of metal with a taper reamer, so you might want to drill up to close to the right size (1.5mm). But go careful because if/when the drill jams in the hole, it is very easy to wrap the coupling rod round the drill, which doesn’t do it a lot of good.

Once the crankpin holes are done, mount the rods on the wheels of two adjacent axles only. With the jointed rods mount the un-jointed section first, in the J10’s case, that’s the first and second axle. Check that those two axles revolve without binding. If you’re close, you can afford to ream all six of the crankpin holes in the rods out a touch more. If persistent jamming is evident, reaming out won’t necessarily fix the problem and you had better start looking for other issues or you’ll ream away too much. When those first 4 wheels revolve smoothly, connect up the last axle using the jointed section of the rods, repeat the process and see what you’ve got.

I don’t plan to go through all the ins and outs of sorting out quartering problems on this occasion, mostly because this one ran nicely first time, and so I didn’t have any problems to sort out. Sorry.

The next photo of the basic rolling chassis was taken at this stage.

csb W&M 9.jpg (148.42 KiB) Viewed 10152 times

You will note that I’ve used plain hexagonal 14BA nuts on the crank pins, as these are easier to deal with. I’ll swap to the proper threaded round crankpin nut later. I’ve still got to reduce the length of the crankpin bushes to suit the rods too. My fancy jointed rods are a touch to thick for the standard Gibson crank pin bushes and I had to invest in a pack of long ones.

Next steps and thoughts about the motor

The next step will be to fit the motor, and to run in the chassis a bit. I have a Mashima 1024 to go in. These are skew wound motors which I find quite as powerful as their larger cousins, and I think they run smoother. They do rev rather fast, which explains my attachment to high ratio gearboxes. Because of where the fixing screws are, you can only really fit it to the gearbox with the flats on the can top and bottom, which seems a bit of a waist. If you really have to have the flats sideways, you have to use the fixing holes above and below the worm gear. This means you can’t fit the top gear shaft and the worm wheel until after the motor has been screwed to the gearbox frame. This is a fiddle worth avoiding.

I don’t subscribe to the idea that you need as big a motor as you can possibly fit. What you must have is a motor that, when the load becomes too great, will spin the driving wheels rather than stalling. If the installed motor can take you past the limit of adhesion, then you can’t use any more power and a larger motor is a waste. For the sorts of layout and size of loco I’m aiming at, herculean feats of haulage and very heavy loco’s aren’t required. Hulking great motors aren’t required either. The ability to spin the wheels rather than stall is a useful safety valve for the motor and should prevent a burnout. If a chassis is a bit stiff, a considerable proportion of the motors power can be used up overcoming the stiffness, so, if a motor runs hot I’d make sure the chassis was running freely before I started wondering if a larger motor was required.

Once the motor has been run a bit and I’m sure the chassis is free running enough, it will be time to fabricate the pickups and to fit details like brake and sanding gear, guard irons, and an ash pan. Fitting pickups is likely to be the subject of the next J10 episode, but there may be a few CSB based diversions before then.

Last edited by Will L on Sat Feb 05, 2011 9:22 pm, edited 2 times in total.

Oh, and Will, those are 'Coupling Rods' rather than Connecting Rods. To avoid confusion, connecting rods connect the crossheads to the crank axle (even car engines have them), coupling rods couple the wheels together.But, whatever they are called and whatever the size of the crankpin holes this is a really useful series.RegardsKeith

I don't believe you 'have' to understand the mathematics, just follow the published charts on the CLAG site or if yours isn't there just request one. A fellow member of L&WMRS used the spreadsheet and had no trouble.

DaveyTee wrote:When I first heard about CSBs, I thought that the idea sounded great and that it was the obvious way to go with my next chassis. I have to say, however, that I find the mathematical complexities utterly off-putting and totally beyond me - it seems to me that if a system that I first perceived as relatively simple is in fact this complex, and requires this amount of mathematical knowledge and precision, then it just isn't for me, which is very disappointing. Or is it just being made to seem more difficult than it actually is?

I'm sorry, I really didn't mean to make CSBs sound complex to apply. For the average user there really is no need to understand how and why it works, just that it does. My view, for what its worth, is that anyone who can build a compensated chassis can build a CSB chassis, and that it will probably be easier to make and work better.

There are no ways to build a chassis out there that are totally problem free, all present problems which you need to learn how to deal with before you can expect to succeed. Even the guys who don't want to go beyond a simple rewheeling exercise will find they need to laern a few tricks of the trade.

I could, perhaps I should, have written a much shorter set of post on how to set out a CSB chassis and let you get on with it. I just don't think they would have been as interesting or as useful in the long run.

Richard.Ough wrote:Considering the last few comments and their worries about a complicated system, I too am wary about something that appears complicated.

I've got a few locos that I'm working my way through using sprung hornblocks, but I do have a pair of High Level Pannier tank chassis to build, so,

I'm going to get a High level CSB jig and give it a bash with and see how it goes.

If you can build them with the sprung horn blocks you can build them with CSB.

The Highlevel jig should make the setting out process simple to get right, not that I though it was that hard to do anyway, but that could just be me. Russ has done a series of fulcrum plots for a pannier. With the HighLevel jig you will need to use the one that sticks to round 0.5mm measurements.

I suspect this must be one of the easiest first CSB chassis to attempt. The HighLevel etches are always a pleasure to put together and you know the bits are going to fit. As he didn't design if for CSB you will just need to check you can get clearance for the CSB wires down the inside of the chassis.

What I do like about the CSB system is that is retains the hornblocks in their guides without recourse to any other form of keeper plate. (At least that is how I see the system appearing to work)

That how it works and is one of the reasons I'm so keen...

I'm still plucking up the courage to start using 16 BA studding to attach the spring etches back to the frames

... but I have been known to put a keeper plate in as somewhere to attach the under hung springs, and so they all come off as a unit by undoing a single screw.

Good luck

Will

Last edited by Will L on Sat Mar 01, 2014 11:43 pm, edited 2 times in total.

Will L wrote:I'm sorry, I really didn't mean to make CSBs sound complex to apply.

You haven't. Throughout this thread you've given an excellent practical illustration of the application of CSBs. I think you've succeeded admirably with your "blow by blow" account. Unfortunately (at least from my point of view) the thread has recently been straying into theoretical aspects that I have found virtually incomprehensible and have left me doubting that I could possibly do the necessary calculations, or ensure sufficient precision (down to 0.5mm, it seems) to achieve success with this method.

Just one thing I would like to say in view of the last few exchanges - despite the misgivings I have expressed about the amount of work involved in installing and adjusting CSB's, I have found this thread absolutely fascinating, and I think Will has done a brilliant job in explaining the assembly of his J10 chassis. In addition to the CSBs, there have been some extremely useful hints and tips along the way.

So all power to your elbow, Will. It's just that I don't think that CSBs are going to be the answer for me. I shall nevertheless continue to follow this thread with great interest.

Will L wrote:Given that this sort of technical discussion is enjoyed by some of us, but other find it very off putting, I'm wondering if we could split the thread down into the blow by blow posts, plus all the directly related posts, and a second "CSB Clinic" thread which could carry all the technical discussion and be clearly welcoming for people to ask their own questions

Excellent idea, Will. I'd almost given up on the practical, "blow by blow" thread that I was enjoying so much and. as Martin said, was providing so many useful tips along the way.